Cylindrically shaped, open topped cartons have frequently been used in the past for packaging of ice cream or the like. Although rectangularly shaped cartons for this purpose have also been employed to some extent in recent periods, the cylindrically shaped, or "round" ice cream carton tends to connote "homemade" or "old fashion" ice cream in the mind of the public and thus remains desirable for use with particular types of ice cream products to convey an impression of quality. In the past, round ice cream cartons of the type made from paper stock have been of an essentially multi-piece construction, typically including a separate bottom wall which is joined to one end of a cylindrically shaped sleeve. Various means have been devised to attach the bottom wall to the sleeve forming the side walls of the carton. These prior constructions have been less than completely satisfactory either because of the inadequate sealing of the bottom to the side walls, which resulted in leaking of the carton, or because the resulting construction was not sufficiently rigid to maintain the bottom in proper position, particularly when the ice cream had melted slightly and permeated the paper stock thereby weakening the same. Moreover, the use of a separate bottom and side walls to form the carton increased manufacturing costs as a result of the necessity of individually form separate sections of the carton and later attach the various sections together before erecting the carton into its completed form.
Known prior art cartons of the cylindrical type are less than desirable for a number of reasons including inadequate sealing between the lid and container, lack of structural integrity particularly in the base thereof, and a non-smooth transition in the shape of the sidewalls from an angularly shaped base on one end of the container to a round cross-section at the other end thereof. Thus, there is a need in the art for a cylindrically shaped ice cream carton which may be formed from a unitary sheet of paper stock and simply erected to form a strong, leakproof package having side walls with a smooth transition in the cross-section geometry thereof.
The present invention provides a round ice cream carton which eliminates the deficiencies inherent in prior art designs and provides a carton construction which is not only particularly economical from a manufacturing standpoint, but is exceptionally strong and not prone to allow leakage of the contents therefrom. According to the present invention, a cylindrically shaped, open topped ice cream carton is formed from a blank comprising a unitary sheet of paper stock cut and configured to present a polygonally shaped bottom panel having a pair of rectangularly shaped side wall panels joined by fold lines to diametrically opposite edges of the bottom panel. When erected, the lower edges of the side walls conformingly join to each of the plurality of edges defining the polygonal periphery of the bottom. The side walls are provided with a plurality of circumferentially spaced, Y-shaped pleats therein adjacent the juncture of the straight edges of the bottom to produce a smooth and rapid transition of the side walls from a polygonal cross-section near the bottom thereof to a circular cross-section in intermediate and upper sections thereof. One or more strips of the paper stock circumscribing the rim of the carton is folded into overlapping relationship with the side walls to provide a double or triple thickness rim for frictionally engaging a lid installed over the top of the carton. Alternatively, the paper stock defining the opening in the carton may be rolled to form a bead-type rim. Specially configured wings or securement tabs on the reinforcement strips provide an especially effective means for maintaining the strips in a flush folded condition against the side walls of the carton.